Question

If x = 1 8+3√7 and y = 1 8−3√7 , then find the value of (i) x 2 + y2 and (ii) xy

Answer 1

Step-by-step explanation:

${x}^{2} + {y}^{2} = 2({18}^{2} + ( {3 \sqrt{7} })^{2} ) \\ \\ = 2(324 + 63) \\ \\ = 2 \times 387 \\ \\ = 774$

$xy = {18}^{2} - ( {3 \sqrt{7}) }^{2} \\ \\ = 324 - 63 \\ \\ = 261$